Differential heating system



C. A. DUNHAM DIFFERENTIAL lHEATING SYS TEU Original Filed' April 4. 1924a lala ala aaaa aaa aaa aaa aa a all aalaaaaaaae. Jaaa aaaaaaaaaa aaaaaa, .aaaaaa f aa a |551 aaaafaaauu/aaahaaauaaauaaaaauuuaauauaaaauaralaaaaaaaai laaaaauaaaaaaaruua/waa.aaaaaraaaaaaaaaaaararlaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaazaaia.

a aaaaaaar: aaalnaaaa aaaaaaaaaaaaaaalaaaraaaa Sept. 9, 1930.

Patented Sept. 9, 1930 uNn-aosTATEs PATENT OFFICE cLAYToN A DUNnAmorGLENcon, ILLINOIS, AssIGNoa To c.'-A. DUNHAII COMPANY,

OF MARSHALLTOWN,

IOWA, A .CORPORATION or IowA DIrnnaENTIAL HEATING SYSTEM l l l Originalapplication led April 4, .1924, Serial No. 704,141.

serial lo. 243,861. Renewed April 22, 1929.

application led Decemberel, 1927,

This invention relates to a steam heating system, comprising separatesupply and return mains, and adapted to normally supply steam atsub-atmospheric pressures to the v radiators. 'Means are provided formaintaindraws only L the head of water-n the boiler. This ap partsadapted to carry the return ing the required vacuum or low pressure inmain, as Well as a certain pressure differential between the supply andreturn mains. This exhausting mechanism with- .air and non-condensablegases, the condensate which accumulates in the return main gravitatingdirectly to the boiler or steam generator. According to thepresentinvention, a return-trap'is provided in the return main, wheresteam pressure is automatically provided, if necessary, tol assistp tliereturn main in returning the, accumulated liquid condensate to plicationis a division of my copending apphcation, Serial No. 7 04,142, filedApril v4, 1924.

The principal object of the invention is to provide la newand improvedvcombination of out the principles of this invention as briefly outlinedhereinabove,

' and as explained in detail in the description which follows.

Other objects andadvanta es of this invention will be more apparent romthe following detailed description of one approved form of theapparatus.

In the accompanying drawings:

Fig. l is a diagrammatic elevation of the assembled apparatus.A Fig. 2is a vertical section through one of the radiator inlet valves.

Referring to the drawings A designates one of the radiators ,of theheating system,and

B is the steam supply main opening out of the steam'space of thelsteamgenerator or boiler C and connected by a supply pipe D with radiator A.A manually controlled in let, valve E limits the supply of steamadmitted from pi e D to radiator A, and F is a steam trap o preferablyof the expansible iiuid-lled disk type, located at the outlet of ,theradiator. This trap is connected by a dpipe 1 with the' return main G.'It is to be un rstood that the radiator A'is Amerely one of .a pluralityof v for each of the radiators of any preferred construction,-

lenewed November 9, 1927. Divided and this similar radiators that may beutilized in the which has threaded engagement with an internallythreaded sleeve 32 adapted to be rotated by a handle 33, the' sleeve andhandle being supported by the bonnet `34 of the valve casing. 'The stem47 is non-circular in crosssection and extends through' an opening ofsimilar shape in a guide plate) 35 which is in terposed between the,upper edge'of the casing and the bonnet. Consequently when the handle33 is turned, nut 3l is forced downwardly so as to seat the valve overport 44. The outlet port of the valve casing is through a boss 36securedby union 37 to a nipple 38, which is screwed lnto radiator A. Aplate or disc 39 formed with an orifice 40 is arrangedin the boss 36andis held against a shoulder 41 by ansplit ring 42. The orifice plate39 is removable so that the valve the heatingsystem may be fitted with aplate having an orifice of the proper size to provide forthe admissionto the radiator of the proper amount of steam. The orifices are of suchsize that when the system is filled with steam, they will admit enoughsteam to the radiators to make up for condensation. That is, thepressure in the radiators will substantial- 1y equal the supply pipepressure. The orifice valve 2 and the boiler. At I is shown athermostatic trap positioned in a pipe 3 between the drip pipe H and thereturn main G for venting air from the drip pipe into the return i main.At J i's an air eliminator connected by pipe 4 withthe return main, andhaving an air outlet pipe 5 provided withan outwardly opening checkvalve 6. At K is shown Aa thermostat, preferably, but not necessarily,employed for controlling the dampers 7 and 8 of the steam generatorthrough the instrumentality of a damper operating motor 9 of commonconstruction.

Liquid condensate is returned to the boiler from return main G and drippipe H b y gravity, as hereinafter described. The air andnon-condensable gases are withdrawn.

from the return main G'through a pipe 10 leading to any suitable type ofexhausting paratus, the one here indicated being closed and describedmore in detail in my parent application Serial= No. 704,142, hereinabovereferred to; At L is indicated a hurling water tank connected by pipe 11with 25 the drip pipe H. The water level in drip pipe H will normallyextend above the pipe 11, so

I that a constant supply of'water 1s main-v tained in the tank L.However, the same water is used over and over again in this pumpinsystem, bein withdrawn from and returne to. the tank so. that there isnormally the pipell.. The centrifugal pump M receives water from tank Land forces the' same through ajet exhauster N, to the suction space 'ofwhich is connected the pipe 10, leading from the return main G, thispipe being provided with a check valve 12 opening .toward thejet'exhauster. Water from the jet ex- 40 hauster passes into an airseparating tank O and thence back to the water tank L. The air and gasesare discharged to the 'atmosphere from tank O through a iioat-controlledvalve, the'outlet also being provided with an outwardly openingcheck-valve. All of this is disclosed more in detail in my co-pendingapplication, Serial No. 704,142, above referred to. This formof lpumpingor exhaustingmechanism is here s own merely by way of example, and manyother forms. of motordriven or other suitable exhausting mechanism couldbe substituted for the one here illustrated diagrammatically. v

The pump M is preferably driven by an electric motor P, the controllingswitch of which is' governed byv a diierential pressure device R, thelow pressure chamber of which Ais connected by pipe 19.with pipe 10leading from the return main G, and the high pressure chamber of the4controller is connected b means of e 20 with some por'- tion of t esystem w ich is substantially at boiler pressure. 'As here shown,'ppe 20connects into the hurling watercircuit. The exhausting I mechanismoperates to l switch Q to shut no appreciable flow of liquid throughreturn main of the heating system, and tol vent this air. The controlmechanism is so adjusted that the exhausting means will continue tooperate until a predetermineddifference inpressure tween the return mainG and the supply main B (that is all parts of the System which are atsubstantially boiler pressure), after which the differential controllerR willoperate the off motor P thus stopping the pumping system. Whenthis pressure differential has fallen below the desired minimum theexhausting mechanism will again be automatically started to renew thewith-` drawal of gases from the return main G.

The horizontal leg 21 of the return main G is considerably above thewater line'of the boiler so that waterof condensation .from the heatingsystem will flow into the boiler of the generator-by gravity drostatichead of water collecting in the vertical leg or standppe 22 of the4return main above the boiler water level, so long, that is, as theboiler pressure is effectively less than the force exerted by such watercol-` has been established b ey due to the hyumn. The return main isshut olf from boiler pressure by check valve 2. The accumulation ofwater in the drip pipe H will continue until this'water ba ances theboiler pressure, after whichthe excess water accumulation will flow bygravity into the boiler.

At the top of the vertical leg 22 of return main G is positioned areturntrap T, into which the horizontal leg 21. of the return main discharges.with a one-way check valve 23, opening toward the trap T, and preferablythe pipe 21 is provided with a downwardly bent portion 24 to overcomethe resistance of valve 23 to the water accumulation behind the valve.The trap is ,in open communication with the vertical leg 22 of returnmain G. The return trap T is of a type in common use, the one here shownby way of example being disclosed in the patent to "Johnson, 1,509,299,granted )September 23, 1 924. Any other trap of this trap and the pipes25 and 27 are provided with valves under control of a pivoted float 28.When the float is down, that is when there is no material accumula-tionof water in the tank T, the steam pipe 27 will be closed and the airvent pipe 25 will be open. Wheny suiicient water has accumulated Ain thetrap -to raise the float a predetermined distance,

the valve. controlling the air vent-pipe is f closed and the valvecontrolling the steam The return pipe 21 is provided i system since thetraps hausting mechanism will function since there will be no pressuredierential between the supply and 4return mains at this time. Air

l will be exhausted fromthe return main G,

and also through main G from the entire F are open, and the loweredpressure in the b'oiler will cause steam to be supplied to the radiatorsat a lower temperature than if the boiler were subject to atmosphericpressure. When the radiators A have lled with steam, the traps F willclose. The exhausting mechanism will continue to o crate until thereturn main G (now shut 0E fiiom the supply side of the system) isfurther exhausted and the desired pressure differential has beenestablished between the supply and return sides of the system, whereuponthe differential controller R will function to sto the exhaustingmechanism. As

the steam 1n the radiators A condenses, the water will'flow into thetraps F thus causing these traps to open and permit the water to iiowthrough pipes 1 to the return main G, the trap F immediately closing assoon as steamattempts to pass therethrough. The vacuum created by thecondensing steam in the radiators will act to maintain a sub-atmosphericpressure in the radiators, and by suitably controlling the lires insteam generator C any desired sub-atmospheric pressure of the steamWithin the radiators may be maintained, thus varying the heat given outbythe radiators in accordance with temperature requirements.

The water of condensation will gravitate into the vertical leg 22 of thereturn main G and will accumulate until the column of water in pipe 22stands above the water level inthe boiler to an extent suiiicientvtooverbalance thc boiler pressure, whereupon the excesshead of water willopen the one-way valve 2 and gravitate into the boiler. Water ofcondensation will also accumulate in the drip pipe H (which is at boilerpressure) until the head of water in this pipe is sufficient to forcethe excess water into the boiler against the boiler pressure. Water willaccumulate to a height slightly above the pipe 1l, so that theexhausting mechanism will always be primed.

Any air accumulating in drip pipe H will be vented through pipe 3 andtrap I into the return main G, so that it will be Withdrawn and vented,along with the air and non-condensi- 4ble gases in return main y Waterin tank T as exists in the return main G, vso that water will iow freelythru horizontal leg 2l of return main G into the trap T. As long as thepressure differential between the supply and return mains is at or lessthan normal, that is represents a pressure equal to or less than thehydrostatic head of the water column in pipe 22, the condensate willgravitate into the boiler. Under these conditions the trap T does notfunction as such but is merely a part of the return conduit. If,however, due to excess of steam generated over condensation the normaldil"- ferential is exceeded, and this condition persists, the liquidcondensate will accumulate in the pipe 22 and trap T since the watercolumn in the trap will be insuiiicient to balance theA increased boilerpressure. This causes the lioat 28 to rise, closing the vent pipe 25 andopening the trap to the steam pipe 27 so that steam at boiler pressureenters the trap. Since boiler pressure is now exerted on the accumulatedcondensate, the water will gravitate into the boiler. During thisoperation, any condensate accumulating in the return main G above thetrap T is prevented from escaping through the air vent of aireliminatorJ -by the float controlled valve of said eliminator (which is of theusual construction). Check valve 30 prevents water from flowing outthrough pipe 29 from the eliminator J. Y

When the tra T has been discharged into the boiler, the iibat 28 willbelowered, thus closing steam pipe 27 and opening the vent pipe 25. Thetrap T is vented of excess pressure through pipe 25 and valve 26 to theatmosphere', the further reduced to that of the return main throughequalizing pipe29 and valve 30 leading to the air eliminator J..

With the exhausting mechanism out of action, and the system operating atnormal or By means of the equalizing connecpressure in the trap beingsuper-atmospheric pressures, the action of Y steam heating systems, forforcing liquid condensable gases from the return main, .a

iconnections herein disclosed, the trap condensate back I believe that Iam the first in the -manner hereinabove set forth in a system ,op-

erating under sub-atmospheric pressures. By means of the pressureequalizing and venting T may be utilized to return liquid condensate tothe boiler under boiler pressure; ing the low pressure conditionsmaintained in the return side of the heating system.

l. In a steam heating apparatus, a steam generator including a boiler, aradiating system, means comprising an exhausting :apparatus forVmaintaining a pressure below atmospheric in the radiating system and adifference of pressurev between the inlet and outlet ends thereoflsullicient to-move the heating medium through the system, saidexhausting apparatus operating to withdraw gaseous fluids only,

anda conduit for liquid condensate through which water from theradiating system will gravitate tothe boiler, a return trap in thisconduit above the normal-water level therein, and connections with thistrap whereby steam at boiler pressure is utilized to return. liquid tothe boiler when this liquid accumulates in the trap.

2. In a steam heating apparatus, a steam generator including a boiler, aradiating system, means comprising an exhausting apparatus formaintaining a pressure below atmospheric in the radiating system and adifference of pressure between the inlet and outlet ends thereofsufficient to move the heating medium through apparatus operating towithdraw gaseous 'fluids only, and densate through which water from theradiating system will gravitate t the boiler, a return trap in thisconduit above 'the normal waterV level therein, and valved connectionsleading from the trap to the boiler `and return main for alternativelyadmitting steam at boiler pressure to the trap or pressure inthe trap tothat of the low pressure side of the system; l

3. In a steam heating apparatus, a steam generator including a boiler, aradiator. a supply main, a return main, exhausting means for withdrawingonly air and nonregulator for said exhausting means which tends to'maintain a constant minimum pressure differential as between thesupplyand return mains, said return main ycomprising-a standpipe connectedwith the lower portion of the boiler which extends above' the waterlevel of the boiler so as to provide for a watercolumn of a height tooverbalance the boiler pressureV when thediflerence in the pressures inthe supply and return mains corresponds toor is less than the aforesaiddifferential,

a return trap` in the standpipe above the norto the boiler by steampres-- without disturbthe system, said vexhausting a conduit for liquidconlowering the above the normal mal water level therein, and valvedconnections leading from the trap to the supply and return mains foralternatively admitting steam at boiler pressure to the trap ing thepressurein the trap to that existing in the return main.-

4, In a steam heating apparatus, a steamy generator including a boiler,a radiator, a supply main, a return main, exhausting means forwithdrawing only air-and noncondensable gases from the return main, aregulator for said exhausting means which tends to maintain a constantminimum pressure diiierential as between the supply and return mains,said return main comprising a standpipe connected with the lowerportionof the boiler which extends above the water level of the boiler so as toprovide fory a water-column of a height to overbalance the boilerpressure when the difference in the pressures in the supply and ret-urnmains corresponds to or is less than the aforesaid differential,a'check-valve opening toward the boiler in the connection between thestandpipe and the boiler, a return trap in the standpipe above thenormal water level therein, and valved connections leading l'from thetrap to the supply and return mains for alternatively admitting steam atboiler pressure to the trap or lowering the pressure in the trap to thatexisting in the return main.

5. In a steam heating system, a steam generator, pipes connecting thegenerator and radiator for respectively delivering steam to the radiatorand returning liquid condensate to the generator, exhausting meansconnected with the return pipe for withdrawing airand noncondensablegases from' the system and for maintaining a pressure differentialbetween the supply and return sides 'of the system, a return trappositioned in the return pipe above the normal water level therein, and

-va1ved connections leading from the trap to the sup ly and return mainsfor alternatively admitting steam at boiler pressure to the trap, orlowering the pressure therein to the pressure existing in' the'returnside of the system.- 6. Ina steam heating' system, a steam generator, aradiator, supply andreturn pipes connecting the generator and radiatorfor respectively deliverin steam to the radiator and returning .liquicondensate to the generator, exhausting means connected with the .returnpipe for withdrawing airV and noncondensable gasesrom the system and formaintaining a pressure differential between the supply and .return sidesof the system, a return trap-,positiened in the return pi water leveltherein, a. chec or lower- 'l a radiator, supply and return valve in theupper'portion 'of' thereturn pi j e 'il opening towar ne trap, mea-nsforprovi in boilerressure inthe trapfwhen ,water ac umulates therein,and means for venting excess pressure from the trap when the water hasbeen forced therefrom, said latter means mcluding an equalizing pipeconnecting the trap with the return main valve.

7. In a steam heating system,

erator, a radiator, supply and eyond the checka steam genreturn pipesconnecting the generator and radiator-for re-y return pipe forwithdrawing -air and noncondensable gases from the system and formaintaining a pressure diierential between the supply and return sidesof the system, a return trap positioned in the return pipe above thenormal water level therein, a vent pipe leading from the trap, an'outwardly opening check-valve in the vent pipe, a steam pipe connectingthe trap with the supply pipe, float-operated valves connecting thesteam and vent pipes vwith the interior of the trap whereby the ventpipe will normally be open and the steam pipe closed, butthe vent willbe closed and the steam pipe opened when liquid accumulates in the trap,a checkvalve in the return pipe opening toward the trap, an equalizingpipe connecting the vent pipe with the return pipe beyond the checkvalve therein, and a check-valve in the equalizing pipe opening towardthe return pipe.

8. In a steam heating system, a steam generator, a radiator, supply andreturn pipes connecting the generator and radiator for respectivelydelivering steam to the radiator and returning liquid condensate to thegen- `erator, exhausting means connected with the greturn pipe forwithdrawing air and non- 4condensable gases from the system and formaintaining a pressure differential between the supply and return sidesof the system, a return trap positioned in the return pipe above thenormal water level therein, a vent pipe leading from the trap, anoutwardly opening check-valve in the vent pipe, a'steam pipe connectingthe trap with the supply pipe, float-operated valves connecting thesteam and vent pipes with the interior of the trap whereby the vent pipewill normally be open and the steam pipe closed, but the vent will beclosed and the steam pipe opened when liquid accumulates in the trap, anaireliminator connected with check-valve inthe return pipe between theair eliminator and trap and opening toward-the trap, an equalizing pipeconnecting the vent pipe with the air-eliminator, and a checkvalve inthe equalizing pipe opening toward the air-eliminator.

9. In a steam heating apparatus, a steam generator, a radiating system,means for maintaining a pressure below atmospheric in the radiatingsystem and a determined difference of pressure between the inlet andoutlet ends thereof, and a return conduit the return pipe, a

the radiating system will gravitate to the generator, a return trap inthis conduit above the normal water level therein, and means including af1pipe connection with the generator and a oatcontrolled valve in thetrap whereby `steam at boiler pressure is utilized to return Water tothe generator when this water accumulates in the trap.

10. In a steam heating apparatus, a steam generator, maintaining apressure below atmos heric in the radiating system and a determineddifference of pressure between the inlet and outlet ends thereof, 4and areturn conduit through which water from the radiating system willgravitate to the generator, a return through which water from trap inthis' conduit above the normal water level therein, and means comprisingpipe connections with the generator and return conduit' andfloat-controlled valves in the trap for alternatively boiler pressure tothe trap or lowering the pressure in the trap to that of the lowpressure side of the system.

11. In a steam heating apparatus, a steam generator, a radiator, supplyand return pipes connected to the generator and radiator forrespectively delivering steam to the radiator and returning condensateto the enerator, means for maintaining a determlned pressuredifferential between the supply and return sides of the system, a returntrap positioned in the' return Vpipe above the normal water leveltherein, and means comprising pipe connections with the generator andreturn conduit and float-controlled valves in the trap for alternativelyadmitting steam at boiler pressure to the trap, or lowering the pressuretherein to the pressure existing in the return side of the system.

12. In a steam heating apparatus, a steam generator, a radiator, supplyand ieturn pipes connected to the generator and radiator forrespectively delivering steam to the radiator and returning condensateto the generator, means for maintaining a determmed pressurediiierential between-the supply and return sides of the system, a returntrap positioned in the return pipe above the normal water level'therein, a check-valve in the upper portion of the return pipe openingtoward the trap, means including a pipe connection with the generatoranda float-controlled valve in the trap for providing boilerpressure inthe trap when water accumulates therein, and means for venting excesspressure from thetrap when tht water has been forced therefrom, saidlatter means including anvequalizing pipe connecting the trap with thereturn main beyond the check-valve.

13. In a. steam Vheating apparatus, a steam a radiator, supply andreturn pipes to the generator and radiator for generator, connectedrespectively delivering steam to the radiator a radiating system, meansfory admitting steam at and returning condensate to the generator,

means Jfor maintaining a determined pres-4 sure differential between thesupply and return sides of the system, a return trap pov sitioned in thereturn pipe above the normal Y and the steam pipe opened when liquid ac-'lates in the trap. v y

heating system, a steam gencumulates in the trap, a check-valve in thereturn pipe opening toward the trap, an equalizing pipe connecting thevent pipe with the return pipe beyond the check-valve therein, and acheck-valve in the equalizing pipe opening toward the return pipe,

14. In a steam heating` system, a steam generator, a radiating system,means for controlling the flow of steam through the radiata determineding lsystem and maintaining diierence of pressure between the inlet andoutlet ends thereof, and a return conduit through which water from theradiating system will gravitate to the generator, a return trap in thisconduit above the normal water level therein, and means including', apipe connection with the generator and a ioatcontrolled valve in the trawhereby steam at boiler pressure is utilize to return water to thegenerator when this water accumu- 15.` In a steam erator, a radiatingsystem, means for controlling the flow of steam through the radiatingsystem and maintaining a determined difference of pressure between theinlet and outletfends thereof, and a return conduit through which waterfrom the radiating system will'gravitate tothe generator, a return trapin this conduit'above the normal'water level therein, and meansincluding pipe connections with the generator and return conduit andfloat-controlled valves in the trap for alternatively admitting steam atboilerv pressure to the trap or lowering the pressure in the trap tothat of the low pressure side.

ofv the system.

' 16. In a steam heating system, a steam generator, connected to thegenerator and radiator or res ectively delivering steam to the radiatoran returning condensate to the generator,

a radiator, 'supply' and return p1 s for alternatively admitting steamat boiler pressure to the trap, or lowering the pressure therein to thepressure existing in the return side of the system.

17. In a steam heating system, a steam generator, a radiator, supply andreturn pipes connected to the generator and radiator for respectivelydelivering steam to the radiator and returning condensate tothegenerator, means in the supply pipe for controllably restricting theflow of steam to the radiator,

means for maintaining a determined pressure differential between thesupply and return sides of the system, a return trap`positioned in thereturn pipe above the normal water level therein, a check-valve in theupper portion of the return pipe opening toward the trap, means,includinga pipe connect-ion with the generator and afloat-controlledvalve in the trap for providing boilerpressure in the trap when wateraccumulates therein, and means yor'venting excess pressure from the trapwhen the water has been forced therefrom, said latter means including aioat-controlled valve in the trap and an equalizing pipe connecting thetrap with the return main beyond the check-valve.

A18. In a steamheating system, aKL steam generator, a radiator, supplyand return pipes connected to the generator and radiator forrespectively delivering steam to the radiator and returning condensateto the generator, means in the supplypipe for restricting the flow ofsteam to the radiator, means for main- Y steam-pipe connecting thetrap'with the supply pipe, ioat-operated valves connecting the steam andvent pipes \With the interior of the trap whereby 4the vent pipe willnormally be open and the steam pipe closed, but the vent will be closedand .the steam pipe opened when liquid accumulates in the trap, a check-,n valve in the return pipe opening toward the trap,

an equalizing' pipe connecting the vent pipe with the return pipe bevondthe checkvalve therein, and a check-valve in the equalizing pipe openingtowardthe return pipe.

CLAYTON A.- DUNHAM.

means in the supply pipe for controllably re-v l stricting the flow ofsteam to the' radiator,

' means for maintaining a' determined pressure differential between thesupply and return .sides of the system, a return trap posi'- tioned inthe return pipe above the normal water level therein, and meansincluding pipecqnnections with the generator and the return P1Pe l0()lsides of the an outwardand float-controlled valves in the trap A

